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#https://www.notion.so/n8n/Frontmatter-432c2b8dff1f43d4b1c8d20075510fe4
contentType: reference
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# Item linking errors
In n8n you can reference data from any previous node. This doesn't have to be the node just before: it can be any previous node in the chain. When referencing nodes further back, you use the expression syntax `$(node_name).item`.
<figure markdown>
<figcaption markdown>Diagram of threads for different items. Due to the item linking, you can get the actor for each movie using `$('Get famous movie actors').item`.</figcaption>
</figure>
Since the previous node can have multiple items in it, n8n needs to know which one to use. When using `.item`, n8n figures this out for you behind the scenes. Refer to [Item linking concepts](/data/data-mapping/data-item-linking/item-linking-concepts.md) for detailed information on how this works.
`.item` fails if information is missing. To figure out which item to use, n8n maintains a thread back through the workflow's nodes for each item. For a given item, this thread tells n8n which items in previous nodes generated it. To find the matching item in a given previous node, n8n follows this thread back until it reaches the node in question.
When using `.item`, n8n displays an error when:
- The thread is broken
- The thread points to more than one item in the previous node (as it's unclear which one to use)
To solve these errors, you can either avoid using `.item`, or fix the root cause.
You can avoid `.item` by using `.first()`, `.last()` or `.all()[index]` instead. They require you to know the position of the item that you’re targeting within the target node's output items. Refer to [Built in methods and variables | Output of other nodes](/code/builtin/output-other-nodes.md) for more detail on these methods.
The fix for the root cause depends on the exact error.
### Fix for 'Info for expressions missing from previous node'
If you see this error message:
> ERROR: Info for expression missing from previous node
There's a node in the chain that doesn't return pairing information. The solution here depends on the type of the previous node:
- Code nodes: make sure you return which input items the node used to produce each output item. Refer to [Item linking in the code node](/data/data-mapping/data-item-linking/item-linking-code-node.md) for more information.
- Custom or community nodes: the node creator needs to update the node to return which input items it uses to produce each output item. Refer to [Item linking for node creators](/data/data-mapping/data-item-linking/item-linking-node-building.md) for more information.
### Fix for 'Multiple matching items for expression'
This is the error message:
> ERROR: Multiple matching items for expression
Sometimes n8n uses multiple items to create a single item. Examples include the Summarize, Aggregate, and Merge nodes. These nodes can combine information from multiple items.
When you use `.item` and there are multiple possible matches, n8n doesn't know which one to use. To solve this you can either:
- Use `.first()`, `.last()` or `.all()[index]` instead. Refer to [Built in methods and variables | Output of other nodes](/code/builtin/output-other-nodes.md) for more detail on these methods.
- Reference a different node that contains the same information, but doesn't have multiple matching items.
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